kris396ss

I have noticed that is seems LT1/4 guys appear to be successfully pushing the forged powdered metal rods up to and in some cases beyond the 900RWHP mark. It doesn't seem like most have the same confidence in the forged powdered metal rods found in LS series engines like the LSA. I have heard of some B15's and such being pushed over 1000 crank hp using the LSA rod but most guys seem to advise ditching them at those power levels.

Just wondering if anyone has seen both rods up close and personal and can attest to any design improvements ? I am assuming the forging process and metallurgy is the same? I'm wondering if the success with these rods is attributed to luck, being able to make more power with less boost/RPM than LS counterparts or an actual construction difference making the rods stronger.



Reason I ask is I am planning to install a Whipple charged B15 LSX into my 96 Impala this summer but for the same cost I could swap in an LT4 crate engine. I'm not looking to get into internal engine work, and I know the LT4 will make less power out of the gate with a stock blower, but the benefit I see to the LSX is its ability to support higher power numbers; the weak point of the LSX being the LSA rods and possibly the 19259381 pistons that I can find virtually no info on. Since I'll probably never reach power levels that will compromise either the LSX block/crank or LT block/crank, if there is some significant improvement in the design of the LT4 rods/pistons, it may be worth going to the LT4 instead even if it means less power for the time being.

Jimbo1367

I'd do the LT4 iffin its the same cost.

kris396ss

From the lists I made, the LT4 swap probably would be about the same. It has some added complications /expenses over the LSX but for the LSX I'm looking at $8300 for the B15 and a little over 7000 for the whipple (plus water pump, coils, throttle body) so the whole thing is close to even. I like the idea of the LSX B15 because of the simplicity of the swap though, LS swaps have been done a million times in B bodies , all the parts are out there/fitment documented and from what I have seen the B15's are capable of 1000 FWHP with the boost turned up a bit.

What's your reasoning? Keep in mind I'm not going to get into head porting, stroker kits or really even a cam at this point. I just want to make as much power as I can with the motor as assembled, whichever one I use, as uncomplicated, reliable and easy as possible. If the LT4 is capable of making more power or supporting more power though, in stock form, without cam swaps or head work, that would definitely sway my decision.

All things considered, I figured both would be pretty similar in the how much power they could handle and how much power they could make department without getting into head porting, cam swaps etc..

I figured the LT1 has the benefit of better efficiency through technology, and since this is practically a daily driver (nice days) that would be nice, but the B15 is just way easier of a swap to pull off. Also the benefit of starting with 4.0 (or maybe 3.3 if the 4.0 won't fit) over the smaller LT4 blower.

MuhThugga

You could always put Gen V rods in the Gen IV. They are on eBay all the time for about $125 for a set, and are 6.125" rods.

kris396ss

But is there any good reason to? somebody has to have handled both rods to know if one is beefier, heavier different design etc.. or if it's pretty much the same.

MuhThugga

It's a longer rod, for one.

kris396ss

True, seems like that would be good for more power with the dwell time, maybe less load on the rod...but I believe the LSA rods are 6.098 so they are pretty close, I wonder how much of a difference that would really make (engine gurus chime in?). I know on SBC we'd go from 5.7 to 6" rods and it was said to be a great improvement but that's a pretty significant jump in length.

KCS

iTrader: (20)

Forcefed86

iTrader: (4)

I'm aware this is 5 years old. Can one simply drop in the higher compression gen V rods and pistons into an gen IV? Assuming the correct bearings were used? Anyone check balance and what not on these? Can I simply drop the gen V pistons on the GEN4 rods? Know the exact CC of dome they have?

thanks

kgkern01

iTrader: (10)

Gen V pistons are designed around the Direct Injection for the fuel/air flow from the injector and ports. You can run Gen V rods in an LS with the correct bearings, but I would use an LS piston for it. Plus the Intake and exhaust are swapped on opposite sides of the chamber from LS.